Treatment of multiple sclerosis

ABSTRACT

The present invention is a method of preventing or ameliorating the episodic recurrence of MS, comprising administering an effective amount of selective phosphodiesterase inhibitors of Type IV, e.g., Rolipram, e.g., wherein the severity of the episodic recurrences is ameliorated or the time period between episodes is lengthened.

This is a division of the application Ser. No. 08/327,478 filed Oct. 21,1994, now U.S. Pat. No. 5,672,622, which is a continuation ofapplication Ser. No. 08/231,969, filed Apr. 21, 1994, abandoned.

BACKGROUND OF THE INVENTION

Demyelinating diseases are severe afflictions of the brain and spinalcord, involving the destruction of the myelin sheath which surroundsnerve fibers. As a result of demyelination, various neurologicalsymptoms are manifested, including motor impairment, visual loss, andsensory changes. Multiple sclerosis (MS) is the most common of thedemyelinating diseases. It is a disease characterized by episodes offocal disorder of the optic nerves, spinal cord, and brain. Typically,it produces recurring episodes of neurologic dysfunction, followed byremission (relapsing-remitting), but it may also be chronic. Although MSis a well-studied disease, its precise cause remains undetermined.

At present, there is no method for preventing MS. See Cecil's Textbookof Medicine (Wyngaarden, 1993). Until recently, treatments have beenempirical and not entirely successful. For example, adrenocorticalhormone (ACTH), methylprednisone, and prednisone have been shown to havea beneficial effect on the disease. However, a large number of patientsdo not respond to such treatment. Moreover, there is no evidence thatACTH and steroids have an effect on the ultimate course of the diseaseor that they prevent its recurrence. Additionally, amantadine, baclofen,and diazepam have been administered. Recently, Betaseron® (BerlexLaboratories, Inc., Wayne, N.J.) has been approved for the clinicaltreatment of patients having relapsing-remitting MS. It is, therefore,evident that a variety of approaches have been used to treat MS,targeting different physiological and cellular components. For a reviewof treatments, e.g., see Principles of Neurology, Fifth Edition, (Adamset al., 1993). There remains a need for additional drugs which have aneffect on the disease's severity and progression.

SUMMARY OF THE INVENTION

The present invention relates to a method of treating or preventing MS,comprising administering an effective amount of, e.g., a 2-pyrrolidonecompound, e.g., of formula I below, preferably Rolipram, a Type IVphosphodiesterase.

The invention, in one aspect, relates to racemates and optically active4-(polyalkoxyphenyl)-2-pyrrolidones of formula I which are useful inpreventing or treating multiple sclerosis: ##STR1## wherein R₁ and R₂each are alike or different and are hydrocarbon of up to 18 carbon atomswith at least one being other than methyl, a heterocyclic ring, or alkylof 1-5 carbon atoms which is substituted by one or more of halogenatoms, hydroxy, carboxy, alkoxy, alkoxycarbonyl or an amino group; R' isa hydrogen atom, alkyl, aryl or acyl; and X is an oxygen atom or asulfur atom.

These compounds and the methods of making them are described, e.g., inU.S. Pat. No. 4,193,926 and WO 92/02220.

A preferred compound according to the present invention is Rolipram.Rolipram is 4- (3-cyclopentyloxy)-4-methoxyphenyl!-2-pyrrolidinone. See,e.g., Merck Index, 11th edition, pages 1312-1313. It is commerciallyavailable from Schering AG, Berlin, Germany, or may be prepared, e.g.,according to Belgian Patent No. 826,923 or U.S. Pat. No. 4,193,926. Itis useful conventionally as an antidepressant, e.g., U. Schwabe et al.,Mol. Pharmacol. 12, 900 (1976); H. Wachtel, Neuropharmacol. 22, 267(1983); H. Wachtel and H. Schneider, Neuropharmacol. 25, 1119 (1986); W.Krause and G. Kuhne, Xenobiotica 18, 561 (1988). Clinical evaluation ofRolipram for depression is reported in E. Zeller et al.,Pharmacopsychiatry 17, 188 (1984). A comparative clinical trial withamitriptyline, q.v. in severe depressions is reported in F. Eckmann etal., Curr. Ther. Res. 43, 291 (1988). Derivatives of Rolipram can alsobe used according to the invention, i.e., compounds which arestructurally related to Rolipram, and are effective in preventing and/ortreating MS, e.g., those of formula I.

The present invention generally relates to the use of a Type IVphosphodiesterase inhibitor, preferably a compound of formula I,especially Rolipram, in multiple sclerosis (MS), for preventing, and/orameliorating the severity, symptoms, and/or periodicity of recurrence ofthe disease, e.g., lengthening the time period between episodes in whichsymptoms flare, and/or suppressing the ongoing immune or autoimmuneresponse associated with the disease.

The invention thus relates to the administration of an effective amountof such a compound, e.g., one according to formula I, preferablyRolipram, to a patient to prevent or treat MS. The amount of saidcompound, e.g., Rolipram, administered is an amount which is effective,for example, in preventing or ameliorating the symptoms of the diseaseor the disease's recurrence, or affecting the ultimate course of thedisease, e.g., blocking the inflammatory response in the brain, theappearance of inflammatory lesions, neuronal or neuroglia cell death,and/or demyelination and the symptoms typically associated withpathogenesis of the disease.

The present invention also provides pharmaceutical compositionscomprising a compound according to formula I, preferably a Type IVphosphodiesterase inhibitor, preferably Rolipram, which are useful inpreventing or treating multiple sclerosis. According to the method, acompound can be administered, e.g., in a single dose, in multiple doses,e.g., through-the-skin injection or by sustained release means such asan implanted osmotic pump.

Upon further study of the specification and appended claims, furtherobjects and advantages of this invention will become apparent to thoseskilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other objects, features, and attendant advantages of the presentinvention will be more fully appreciated as the same becomes betterunderstood when considered in conjunction with the accompanyingdrawings, in which like reference characters designate the same orsimilar parts throughout the several views and wherein:

FIG. 1 shows the prevention of Experimental Allergic Encephalomyelitis(EAE) by Rolipram in a marmoset. A, B, and C received Rolipram (10mg/kg) in DMSO; D and E received an equivalent volume of DMSO. Marmosetsimmunized with human spinal cord homogenerate received either Rolipramor placebo five days after immunization.

FIG. 2 shows the treatment with Rolipram of marmoset having EAE.

According to the present invention, a pharmaceutical compositioncomprising an effective amount of a compound described above can beadministered to patients having multiple sclerosis, e.g., multiplesclerosis variants such as Neuromyelitis Optica (Devic's Disease),Diffuse Sclerosis, Transitional Sclerosis, Acute DisseminatedEncephalomyelitis, and Optic Neuritis.

Symptoms of MS which are prevented or ameliorated or treated include:weakness and/or numbness in one or more limbs; tingling of theextremities and tight band-like sensations around the trunk or limbs;dragging or poor control of one or both legs to spastic or ataxicparepesis; hyperactive tendon reflexes; disappearance of abdominalreflexes; Lhermitte's sign; retrobulbar or optic neuritis; unsteadinessin walking; brain stem symptoms (diplopia, vertigo, vomiting); disordersof micturition; hemiplegia; trigeminal neuralgia; other pain syndromes;nystagmus and ataxia; cerebellar-type ataxia; Charcot's triad; diplopia;bilateral internuclear ophthalmoplegia; myokymia or paralysis of facialmuscles; deafness; tinnitus; unformed auditory hallucinations (becauseof involvement cochlear connections); vertigo and vomiting (vestibularconnections); transient facial anesthesia or of trigeminal neuralgia;bladder dysfunction; euphoria; depression; dementia, dull, aching painin the low back; sharp, burning, poorly localized pains in a limb orboth legs and girdle pains; abrupt attacks of neurologic deficit;dysarthria and ataxia; paroxysmal pain and dysesthesia in a limb;flashing lights; paroxysmal itching; and/or tonic seizures, taking theform of flexion (dystonic) spasm of the hand, wrist, and elbow withextension of the lower limb. A patient having MS may have one or more ofthese symptoms or other clinical manifestations typically associatedwith MS and one or more can be ameliorated by administrating ofcompounds according to the present invention.

The administration of Type IV phosphodiesterase inhibitors such asRolipram can also block or reduce the physiological and pathogenicdeterioration associated with MS, e.g., inflammatory response in thebrain and other regions of the nervous system, breakdown or disruptionof the blood-brain barrier, appearance of lesions in the brain, tissuedestruction, demyelination, autoimmune inflammatory response, acute orchronic inflammatory response, neuronal death, and/or neuroglia death.

The active agents of this invention, e.g., Rolipram, are useful to treatthe different types of MS, including the multifocal, CNS, relapsing andremitting course; the multifocal, CNS, progressive course; thesingle-site, relapsing and remitting course; and other variants ofmultiple sclerosis. See, e.g., Cecil's Textbook of Medicine, edited byJames B. Wyngaarden, 1988.

Effects of the administration of Rolipram and other Type IVphosphodiesterase inhibitors include, e.g., preventing the disease,ameliorating symptoms of the disease, reducing the annual exacerbationrate (i.e., reducing the number of episodes per year), slowing theprogression of the disease, or reducing the appearance of brain lesions(e.g., as identified by MRI scan). The episodic recurrence of thementioned diseases such as MS can be ameliorated, e.g., by decreasingthe severity of the symptoms (such as the symptoms described above)associated with the, e.g., MS episode, or by lengthening the time periodbetween the occurrence of episodes, e.g., by days, weeks, months, oryears, where the episodes can be characterized by the flare-up andexacerbation of disease symptoms, or preventing or slowing theappearance of brain inflammatory lesions. See, e.g., Adams, R. D.,Principles of Neurology, 1993, page 777, for a description of aneurological inflammatory lesion.

Other specific, suitable, non-limiting examples of Type IVphosphodiesterase inhibitors which can be employed in this inventioninclude compounds described in WO93/19068, compounds RO 20-1724 (4-(3-butyoxy-4-methoxyphenyl)methyl!-2-imidazolidinone), ICI 63197(2-amino-6-methyl-4-propyl 1,2,4!triazolo 1,5-a!pyrimindin-5(4H)-one),denbufylline and etazolate.

By "Type IV phosphodiesterase inhibitor", "specific Type IVphosphodiesterase inhibitor", and similar expressions are meant aselective, i.e., specific, such inhibitor, where the compound binds toor inhibits preferentially the Type IV phosphodiesterase when comparedto known types of phosphodiesterase types, e.g., I, II, or III, e.g.,whereby the compound has a lower IC₅₀ (more potent) for the Type IVphosphodiesterase, such as where the IC₅₀ is, e.g., 2-fold, 5-fold,10-fold, 50-fold, or more potent, for the Type IV phosphodiesterasecompared to another known type of phosphodiesterase, e.g., I, II, orIII. Such selectivity of a compound according to the present inventionfor a Type IV-phosphodiesterase can also be conferred by other means,such as the manner in which it is delivered to its target, e.g., thecompound can be associated with an agent which targets it to a specifictissue or cell type having the Type IV phosphodiesterase; the manner inwhich it interacts with the host's metabolism and/or physiology; orsynthesizing PDE inhibitor prodrugs where activation of the PDEinhibitor is accomplished by enzymes present in the desired cells ortissues but absent in others.

The specific inhibition of a Type IV phosphodiesterase can be measuredconventionally, e.g., according to the methods described in Reeves etal., Biochem. J., 241:535-541, 1977; by macrophage assay, as described,e.g., in Schade et al., Europ. J. Pharmacol., 230:9-14, 1993; or WO93/19068. For a review of phosphodiesterase specificity and how todetermine it, see, e.g., Nicholson et al., Trends Pharmacol. Sci.,12:19-27 (1991).

The activity of this invention of Type IV phosphodiesterase inhibitorssuch as Rolipram can be detected, for example, in animals suffering fromExperimental Allergic Encephalmyelitis (EAE), an experimentalT-lymphocyte initiated disease of the CNS. It can be produced, e.g., inrodents, guinea pigs, rabbits, and primates, by, e.g., immunizinganimals with myelin, e.g., from a human brain, and/or corticosteroidadministration over a long period of time. It can also be produced byinjecting an animal with T-lymphocytes obtained from an animal sufferingfrom EAE.

In particular, the activity can be detected in Callithrix jacchus(common marmoset) which has been immunized with myelin, e.g., from ahuman brain. The Callithrix jacchus develops EAE with essentiallysimilar histopathology and neurological symptoms as those at certainstages of the human disease, MS.

The pharmaceutical compositions according to the present invention areprepared conventionally, comprising substances which are customarilyused in pharmaceuticals, e.g., see Remington's Pharmaceutical Sciences,18th ed., Mack Publishing Company (1990), including excipients,carriers, adjuvants and buffers. The compositions can be administered,e.g., parenterally, enterally, orally, intramuscularly, topically,subcutaneously, intravenously, by aerosol, intrathecally directly intothe cerebral spinal fluid of the CNS, or preferably by sustained releaseusing, e.g., an implanted mini-osmotic pump (e.g., the ALZET pumpmanufactured by ALZA Corporation, P. O. Box 10950, Palo Alto, Calif.94303), or other routes useful to achieve an effect.

Conventional excipients include pharmaceutically acceptable organic orinorganic carrier substances suitable for parenteral, enteral or topicalapplication which do not deleteriously react with the agents. Suitablepharmaceutically acceptable adjuvants include, but are not limited to,water, salt solutions, alcohols, gum arabic, vegetable oils,polyethylene glycols, gelatine, lactose, amylose, magnesium stearate,talc, silicic acid, viscous paraffin, perfume oil, fatty acidmonoglycerides and diglycerides, pentaerythritol fatty acid esters,hydroxy-methylcellulose, polyvinyl pyrrolidone, cyclodextrins, etc. Thepharmaceutical preparations can be sterilized and, if desired, mixedwith stabilizers, wetting agents, emulsifiers, salts for influencingosmotic pressure, buffers, coloring, flavoring and/or aromaticsubstances, etc., which do not react deleteriously with the activecompounds.

For parenteral application, particularly suitable are injectable sterilesolutions, preferably oil or aqueous solutions, as well as suspensions,emulsions or implants, including suppositories. Ampoules are convenientunit dosages.

For enteral application, particularly suitable are tablets, dragees,suppositories or capsules having talc and/or a carbohydrate carrier orbinder. The carrier may be lactose, corn starch, potato starch or acombination thereof. A syrup or elixir may be used when a sweetenedvehicle is employed.

The compositions can also be formulated in an aqueous solution,optionally with the addition of additives customary in galenicals, forexample, buffers; electrolytes such as sodium chloride; antioxidantssuch as ascorbic acid; adjuvants, e.g., methyl cellulose, lactose andmannitol and/or surfactants, e.g., lecithins and Tweens and/or aromaticsubstances for flavoring, e.g., ethereal oils.

The pharmaceutical compositions of the present invention can alsocomprise other active agents.

The dosage of the pharmaceutical composition can vary according to,e.g., the manner of administration, the disease being treated and itsseverity, the overall health and condition of the patient, the age ofthe patient or other usual criteria. Total dosages of phosphodiesteraseinhibitors for all uses mentioned herein typically are from about 0.01mg/kg to about 2.0 mg/kg per day, preferably 0.1 mg/kg to 0.7 mg/kg perday, more preferably, 0.5 mg/kg/day. Analogous amounts of other Type IVphosphodiesterase inhibitors can be determined routinely based on theinformation given herein, e.g., using the EAE model. However, any amountwhich is effective in treating MS can be administered to ameliorate ortreat the disease. Dosages are determined conventionally, see, e.g.,Remington's Pharmaceutical Sciences, 18th ed., Mack Publishing Company(1990). The composition may be administered in a single dose unit or inmultiple dosages administered, e.g., twice, three, or four times a day,or by an osmotic pump, which delivers the drug(s) continuously.

Without further elaboration, it is believed that one skilled in the artcan, using the preceding description, utilize the present invention toits fullest extent. The following preferred specific embodiments are,therefore, to be construed as merely illustrative and not limitative ofthe remainder of the disclosure in any way whatsoever.

In the foregoing and in the following examples, all temperatures are setforth uncorrected in degrees Celsius; and, unless otherwise indicated,all parts and percentages are by weight.

The entire disclosures of all applications, patents, and publicationscited herein are hereby incorporated by reference.

EXAMPLES

Rolipram was produced by Schering AG (Berlin) and is comprised of (+)and (-) racemates of 4-(3-cyclopentyloxy)-4-methoxyphenyl!-2-pyrrolidinone. It was dissolved indimethylsulfoxide (DMSO) at 20 mg/ml.

Human brain white matter homogenate was prepared from autopsy materialin complete Freund's adjuvant (CFA) containing M. tuberculosis (strainH37 Ra).

Bordetella pertussis vaccine was obtained from the Massachusetts PublicHealth Department, Biological Laboratories, Boston, Mass.

Zofran was obtained from the University of California Medical CenterPharmacy.

The marmosets were purchased from the New England Regional PrimateResearch Center and were maintained and cared for in accordance with theguidelines of the Internal Animal Care and Use Committee of theUniversity of California, San Francisco.

Animals were immunized with human brain white matter homogenate (200 mg)in CFA containing 3 mg/ml killed M. tuberculosis (H37 Ra strain) byintradermal injection (0.6 ml) over four sites on the doral axilla andinguinal region. On the day of immunization and again 2 days later10×10¹⁰ inactivated Bordetella pertussis (Bordetella pertussis vaccine)were infused intravenously in 10 ml saline.

On day 5, following immunization, animals were injected subcutaneouslyin the back of the neck with DMSO (placebo) or with DMSO containingRolipram to give a dose of 10 mg/kg. Treatment with DMSO or DMSO withRolipram was preceded 20 min. by an injection of 0.3-0.6 mg/kg Zofranintramuscularly (Odansetron Hydrochloride, Glaxo) to prevent salivation,vomiting, excessive grooming, and head twists. Such treatments wererepeated every 48 hours throughout the study.

Animals were observed daily and subjected to a standardized scoringsystem to record the severity of clinical symptoms:

0. Normal

1. Lethargy, anorexia, weight loss

2. Ataxia, tremor

3. Blindness, paraplegia or hemiplegia

4. Quadraparesis or quadriplegia

5. Moribund

At various times, animals were anesthetized and subjected to MRI.

EXPERIMENT 1 Prevention of EAE by Rolipram Treatment

Marmosets were immunized with spinal cord homogenate as described. Onday 5, following immunization, three marmosets received Rolipram (10mg/kg) in DMSO. See FIG. 1, A, B, and C. Two marmosets received anequivalent volume of DMSO after the same interval. See FIG. 1, D and E.The treatment was repeated every 48 hours.

The animals treated with DMSO (placebo) developed clinical symptomsconsistent with EAE 15 days following immunization; see FIG. 1, D and E.None of the Rolipram treated animals developed symptoms during the 8week interval of observation; see FIG. 1, A, B, and C.

Magnetic Resonance Imaging (MRI) analysis showed that the two animalswith EAE symptoms developed one or more lesions in the brain which"enhanced" with Magnevist (gadolinium, DTPA), indicating an activeedematous response consistent with the vascular inflammatory lesionsseen in EAE or MS (Alvord, etc.). None of the Rolipram treated animalsdeveloped detectable lesions during the 8 week interval of observation.

Development of EAE After Withdrawal of Rolipram

On day 60, following immunization, the treated animals were removed fromtreatment and observed for signs of EAE. Two marmosets began to showclinical signs of EAE on day 17, following withdrawal of Rolipram.

EXPERIMENT 2 Treatment of Active EAE with Rolipram

In the previous experiment, it was clearly demonstrated that Rolipramcould prevent EAE. It is of interest to determine if Rolipram can alsoaffect active EAE. In this experiment, a marmoset was immunized aspreviously described, allowed to develop symptoms of chronic EAE andsubsequently treated with Rolipram. The animal was treated withescalating doses of Rolipram in DMSO administered as described in theprevious experiment. The physical symptoms were monitored as describedand MRI analysis was done at times before and after treating (FIG. 2).

The animal showed marked improvement on day 10 after initiatingtreatment. The animal showed MRI improvement on day 14 followinginitiating Rolipram treatment and, from that time, the conditionstabilized with slower improvements.

The results of Experiment 1 indicate that Rolipram treatment blocked theneurological signs of EAE. The MRI results indicate that theinflammatory response was blocked and demyelination did not occur. Theuntreated control animals developed clear signs of EAE and inflammatorylesions as indicated by MRI analysis. The fact that treated animalsdeveloped EAE when removed from treatment showed that the immuneresponse to brain homogenate had occurred sufficiently to initiate thedisease; however, some subsequent step in pathogenesis was blocked.

The results of Experiment 2 indicate that Rolipram treatment can inhibitactive disease.

The preceding examples can be repeated with similar success bysubstituting the generically or specifically described reactants and/oroperating conditions of this invention for those used in the precedingexamples.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention and, withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions.

We claim:
 1. An implantable osmotic pump comprising 4-(3-cyclopentyloxy)-4-methoxyphenyl!-2-pyrrolidinone and apharmaceutically acceptable carrier.